The population of elderly in the United States will be more than doubled, numbering to 72.1 million, from 2000 to 2030. The roughness of voice and decline of voice quality are ubiquitous signs of aging. The vibratory characteristics of the vocal folds are largely governed by the stiffness conditions in the vocal folds lamina propria (LP). The stiffness is determined by the nonlinearity and anisotropy of vocal fold LP mechanical properties resulting from the structural properties of the extracellular matrix. Therefore, knowledge of alterations in the LP mechanical and microstructural properties with age can elucidate the primary causes affecting mucosal wave, vocal fold vibration and voice quality in elderly. The goal of this research proposal is three-fold: First, to determine the inherent nonlinearity and anisotropy of the LP mechanical properties and their influence on the pitch range and closure pattern, based on in vitro phonation measurements, as a function of age; secondly, to determine the underlying contribution of elastin and collagen material properties to the mechanical behavior, and delineate the alterations in these properties with age.